Play lots of games and have lots of activities. Its best to change your activity every 5-10 minutes so you can keep their attention better. Try to alternate your activites between the main focus of the class and review material so you don't bore them.
So if the goal of one class is to teach them how to say 'How are you' you might start with review of how to say 'hello' then introduce 'how are you' with a game, then review colors or something, and go back to 'how are you' again. And remember, coloring is your best friend. When all else fails, give them some crayons and let them color for a while.
Theres a great book out there called 'Teaching English to Children in Asia.' Can't remember the author, but see if you can find it because it has really hepled me in my younger classes.
Good luck.

I am having similar problems, and thanks for recommending that book. I saw it in Kim and Johnson's in Busan last week, I was wondering if it was worth buying.

One other thing I would add, (not that I'm an expert) Use songs with actions, kids love them. The livelier the better. Sometimes even the craziest little ditty that I remember from my youth is a real hit with the kids. If you want, there are several song and chant books out for kids.
I prefer songs, I don't know why, but chants never seem to go over well.
There are the "lets Chant" books as well as "Wee Sing" . They usually come with tapes so if you aren't the best singer, the tape can help you.
It's better if you can sing the songs though, rather than fumbling through a tape. Some of the chants are OK if you make a song out of them. I use common tunes like "Farmer in the Dell", "Mary had a little lamb", "He's a Jolly good fellow", "Old MacDonald" , "If you're happy and you know it" etc. Sometimes it takes a bit of work to make a chant fit a tune or visa versa, but it's worth the effort. The kids are a lot more receptive to a chant if it is sung to a melody that they already know.
Anyway, I hope this helps.
Best of luck to you.
Some Waygug-in

I have one word for you: STRUCTURE!!!! Take your time and teach these kids what you expect from them. TEACH them that you expect them to line up to go to the potty. TEACH them how to get their crayons with a semblance of order. TEACH them to put their finished assignments in a certain place.... The list goes on, and this will take concerted effort on your part, not to mention a long time, but believe me when I say it will be worth it in the long run. When the kids learn how your classroom runs, it will basically run itself. Even if you get a new student or students in, the 'oldhands' in the class will tell them how things work. With some classes this means starting from scratch, with others you merely have to fine-tune it to suit your teaching style. Not only will getting them into a routine help control them, but it will aid in getting the actual ENGLISH teaching done in the long run. Also, in your first few weeks of class you can use up time running practice drills on everything. This may sound silly, but trust me, it WORKS. I have taught kindergarten in Korea for 2 years and those 3 hour classes every morning sure get easier when the kiddies know what to expect. Remember, having a set routine and structure does not HAVE to mean a boring classroom, it means that the kids feel secure and thus can focus on learning. Hope this helps, I know it helped me when I was given the same advice.

Oh yeah, and have FUN with them!!! The young ones can really be a joy to teach.

If you are allowed to choose a book then have a look at Tiny Talk. Endearing lead characters and realistic social situations - the absentee father turns up halfway through book 2
Get some hand puppets to model the dialogues then get kids to perform them in pairs in front of the class.

Also the songs are brilliant, nearly as good as those in Lets Go 3, and you will be singing them for weeks.

Yes teach them everything that you expect.
I hated kindergarden when I first arrived and still do some days.
It gets better the longer you have them thou.
I found that letting them have turns being teacher helps to get the lazy sleepy kids into it.
Put on kid on your knee and whisper into there ear.Haveing them repeat everything to the rest of the kids. it has shocked me at times, what they can say when they want to.
enjoy

Use realia (objects) to get your points over as well. I teach kids part time at a Korean Uchiwon, which is equipped with everything under the sun. Every room has a keyboard, and all of the toys you could possibly want. They have plastic copies of fruit for example, and animals as well. They love it when they can get their hands on something.

I hold up a plastic apple, and ask them what it is. They can't just say apple. I demand that they say " I like apples". Get em to use the word in a sentence. If they do that I throw the apple to the youngster. Repeat it with all of them for different fruits, then collect them asking first for say the bananas, making sure they hand back the right fruit. then ask for another and so on. You can do this for animals, and vegetables as well.
Buy your own if your institute doesn't have them.

The next step is to get them to ask each other what their favourite color,or fruit or animal is. Start by saying "What's your favorite color?" The youngster has to answer, and then turn and ask the next person the same question. Repeat day in and day out.